1. Field of the Invention
This invention relates to bulk bins, and particularly to a self-locking bottom flap construction for octagonal bulk bins.
2. The Prior Art
Bulk bins are used in the industry for storing and shipping numerous products, and typically hold 2,000 pounds or more of the product, including flowable or semi-liquid products such as, e.g., comminuted poultry. When flowable products are to be contained in the bin, a bag normally is placed in the bin for receiving the product. The outward force exerted on the sidewalls by flowable products, in particular, is substantial, and tends to bulge the sidewalls outwardly. The bins are commonly made of corrugated cardboard and comprise a plurality of sidewalls joined together along vertical folds. The bottoms of the bins preferably are closed or partially closed by inwardly folded bottom flaps joined to bottom edges of the side walls along horizontal folds. The flaps are separated from one another by slots or cuts extending from an outer edge of the flaps to a point at or near the intersection of the vertical and horizontal folds. This structure creates a weak point where tearing of the vertical fold can initiate. Tearing of the vertical fold can propagate rapidly upwardly, resulting in bursting of the sidewall and failure of the bin, with consequent loss of the stored product.
At least partially to minimize the outward bulge of the sidewalls, the industry has adopted bulk bins having an octagonal shape, wherein diagonal corner panels are interposed between adjacent edges of the opposed sidewalls and opposed end walls. In conventional octagonal bins the diagonal corner panels are of less width than either the sidewalls or the end walls of the bin, and although the octagonal configuration reduces the width of the sidewalls and/or end walls in a bin having a comparable capacity and size to a corresponding four-sided bin, thus reducing the extent of outward bulge of the sidewalls and/or end walls, the sidewalls and/or end walls still have substantial width.
Bulk bins made of corrugated material are typically manufactured from a single blank that is scored to delineate the sidewalls, end walls, diagonal corner panels, and bottom flaps. The blank is folded and secured at a manufacturer's joint by the manufacturer, and shipped to the user in a flattened condition. The user then sets the flattened bin on end and opens it up into an expanded tubular configuration. The bottom flaps are then folded inwardly and secured to hold the bin in its set-up condition. Self-locking bottom flaps have been developed to facilitate setting up the bin from its flattened condition to its fully open usable condition.
Octagonal bulk bins normally have eight bottom flaps, including two major flaps, two minor flaps, and four diagonal flaps. Conventional octagonal bulk bins with or without self-locking bottom flaps are cumbersome to assemble, and as a result users often seek alternative packaging. Further, the sequence of inward folding of the bottom flaps on a conventional octagonal bulk bin frequently results in creating extra pinch points in the bottom of the bin, e.g., by the diagonal flaps extending into the interior of the box bottom, which can damage the bag and cause it to rupture, thus contaminating the stored product.
It would be desirable to have a bulk bin that has all the advantages of an octagonal bulk bin, but that is free of the problems associated with conventional bulk bins, and particularly to have an octagonal bulk bin with bottom flaps, especially self-locking bottom flaps, that is relatively easy to erect into its operative position, is constructed to avoid the formation of weak points where tearing of the vertical fold can initiate and to avoid the formation of pinch points in the bottom.